The present invention relates to surface active compounds, their preparation and their use, and more particularly to surface active compounds which can have their structures readily modified to permit not only the separation and recovery of lipid material from an aqueous medium in which such compounds are used but also to provide, after such separation, an aqueous phase in which the contents of such lipid material and of active surface active material are substantially reduced.
A variety of surface active agents or compounds are well known and such compounds are used for a variety of purposes. Merely by way of example, there can be mentioned the uses of such compounds in household detergents and other cleaning compositions and in industrial products such as detergents, emulsifying agents, wetting agents, coupling agents and substantive agents as used in fabric treatment. Surface active compounds are generally used in aqueous media and it is fully recognized that the disposal of large quantities of waste waters containing surface active compounds presents numerous problems in sewage treatment plants and in natural bodies of water such as rivers and lakes into which such waste waters frequently find their way.
All surface active compounds have a molecular structure which comprises a lipophilic or hydrophobic portion or moiety bonded to a hydrophilic portion or moiety. It is believed that, in the use of a surface active compound in an aqueous medium, the hydrophilic portions of the molecules effectively become attached to water molecules so effectively providing dissolution of the compound in the aqueous medium. It is also believed that the lipophilic portions of such molecules become attached to any lipidic material which is present so as effectively to maintain that material in dispersion in the aqueous phase. For example, in the use of a household detergent, the lipophilic portions of the surface active compound molecules become associated with oil, grease or dirt molecules with the result that such molecules effectively become dissolved or at least dispersed in the aqueous phase. Since an excess of detergent will often be used, that aqueous phase will normally also contain molecules of the surface active compound with which no lipid molecules are associated. The principal problem which arises with such use of detergents is a result of the presence in the waste water of the surface active compound regardless of whether or not the molecules thereof have any lipid molecules associated therewith.
On the other hand, in the use, for example, of a surface active compound as an emulsifying agent to form an aqueous emulsion of an industrial cutting oil, the association with the molecules of the surface active compound of molecules of both water and the lipid material (i.e. the cutting oil) provides a stable emulsion which, if discarded after use into a waste water system, results not only in serious pollution of the waste water with both the surface active compound and the cutting oil but also to a significant loss of the valuable cutting oil itself.
Presently known surface active compounds fall, as is well known, into four classes, namely anionic, cationic, amphoteric and non-ionic which differ essentially in the manner in which their hydrophilic portions effectively associate with water molecules.
As hereinbefore indicated, the problems involved in the disposal of waste waters containing surface active compounds and lipid materials dispersed in such waters are fully recognized and attempts have heretofore been made to treat such waste waters to separate such surface active compounds and lipid materials from such waters. Some success has been attained in the purification of waste waters containing anionic and cationic surface active compounds by treating such waste waters with flocculating agents so as to rupture the so-called bonds between the hydrophilic moieties of the surface active compounds and the water molecules so as then to allow separation of a lipid phase and/or the surface active compound from the aqueous phase. Various adsorption processes have also been suggested for purifying waste waters containing surface active compounds and lipid materials. It has also been suggested to provide bio-degradable surface active compounds which can be destroyed by certain bacteria.
The known processes for the deactivation and/or removal of surface active compounds from waste waters have, however, presented various problems. For example, the previously proposed adsorption processes are relatively slow and, for the treatment of large quantities of waste waters, call for substantial capital investment. Additionally, if it is then desired to recover the lipid material, it is then necessary to recover that material from the adsorbent at further expense.
Additionally, many of the previously proposed processes are not effective for deactivating non-ionic surface active compounds and consequently very substantial volumes of waste waters containing such compounds and lipid materials associated therewith are discarded each year into sewage plants and natural bodies of water. Additionally, the use of non-ionic surface active compounds is precluded in many applications in view of the difficulty of purifying waste waters containing such compounds.
It is a principal object of the present invention to provide a surface active compound which can readily be deactivated when present in waste waters so as then also to permit the ready removal from such waters of lipid material previously dispersed therein and to reduce the amount of active surface active compound which remains in the waste waters which are to be discarded.
It is a further object of this invention, in accordance with a preferred feature thereof, to provide an improved and de-activatable surface active compound.
Other objects of the invention will become apparent as the description herein proceeds.